Liquid crystal display device

ABSTRACT

In the present invention, it is an object to improve display quality by improving response speed of a liquid crystal element in a liquid crystal display device, in particular, response speed in the case of falling. 
     In the present invention, it is characterized that a liquid crystal layer is divided into plural regions (domains) substantially by mixing a compound including a liquid crystal skeleton in a liquid crystal layer exisiting liquid crystal molecules as a technique to improve response speed of a liquid crystal element in a liquid crystal display device for solving the above problem.

TECHNICAL FIELD

The present invention relates to a technique for improving a responsespeed of a display device (including a liquid crystal element) applyinga liquid crystal.

BACKGROUND ART

A display device applying a liquid crystal material is used extensivelyas a light-weight and thin display device. The liquid crystal displaydevice interposes a liquid crystal material between two pieces of flatplates such as glass substrates. By applying an electric field by atleast one electrode arranged on a flat surface where the liquid crystalof a flat plate is arranged, a liquid crystal molecule is switched bythe intensity and existence or nonexistence of the electric field. Sinceoptical property of the liquid crystal is changed in conjunction withit, displaying of an image or the like is performed using this change ofoptical property.

A nematic liquid crystal is generally used as a liquid crystal materialused for a liquid crystal element. A nematic liquid crystal means one ofthe categories distinguished by arranging status of liquid crystalmolecules constituting a liquid crystal material. In addition, forexample, there is a material such as a smectic liquid crystal. However,a nematic liquid crystal has a liquid property and flowability within anoperating temperature range and is used extensively as a display ineasiness of initial orientation of liquid crystal molecules andstability of orientation state, and breadth of operatable temperaturerange.

A hight of a contrast is given as one of the factorsto determine displayperformance of a display. A contrast is represented by a ratio ofluminance of a light state and luminance of a dark state, and ahigh-grade image can be provided as the ratio becomes higher.

However, conventional TN (Twisted Nematic) mode and the like weredifficult to get an ideal dark state since it is affected by a slightphase difference that a liquid crystal represented. This is because inthe case of a TN mode, though a molecular major axis is shifted from aparallel state to a perpendicular state in an orientation state ofliquid crystal molecules by means of applying an electric field, it isnot easy particularly that a molecular in a place near to a substratesurface is shifted perpendicular to the substrate so that birefringenceof liquid crystal in that portion remains.

Thus, a liquid crystal display device using a perpendicular orientationmode is suggested as a method to make contrast ratio better. (forexample, see Non-Patent Document 1).

In a perpendicular orientation mode, a liquid crystal molecule isoriented in perpendicular direction with respect to a substrate surfaceof a liquid crystal display device beforehand, therefore, when anelectric field is not applied to an electrode, transmitted light isinterrupted by a polarizing plate. Meanwhile when an electric field isapplied to an electrode (at a time of driving), a liquid crystalmolecule exists with the state that declined from the perpendiculardirection. It is a display method using that light-transmitting propertyis obtained by birefringence of these liquid crystal molecules.

In addition, in the perpendicular orientation mode, the state in whichan electric field is not applied is a perpendicular orientation stateand a black display is obtained. In the perpendicular orientation state,since a birefringence of liquid crystal does not appear, it is a drivingmode in which light leak is small and a black display is theoreticallyeasy to obtain.

Furthermore, in the case of a liquid crystal display device usingnematic liquid crystal, a challenge is reducing time required for anoperation of a liquid crystal molecule (hereinafter, response time) whena display signal is switched from one displaying state to the nextdisplaying state. Note that, the response time which is needed whendisplay is switched from state of OFF to a state of ON is referred to as“rising response time” and when display is switched from state of ON tothe state of OFF is referred to as “falling response time”. A method inwhich “rising response time” is shortened by driving wave form has beensuggested. (for example, see Non-Patent Document 2).

In the case where display is made a state of ON from a state of OFF (inthe case of rising), if electric field is made strongly, response speedcan be made quickly since an orientation direction of liquid crystalmolecules is controlled by electric field. However, in the case ofdisplay is made to a state of OFF from a state of ON (in the case offalling), control to improve response speed is difficult as compared tothe case of rising since the OFF state can be obtained by returningliquid crystal molecules released from the control by the electric fieldto the orientation state before electric field has been applied. Thus,more improvement has been needed.

[Non-Patent Document 1]

K. Ohmuro, S. Kataoka, T. Sasaki, and Y. Koike, SID' 97 Digest of Tech.Papers, (1997) 845,

[Non-Patent Document 2]

S. Sang, SID' 04 Digest of Tech. Papers, (2004) 760

DISCLOSURE OF INVENTION

[Problem to be Solved by the Invention]

Thus, it is an object of the present invention to improve displayquality by improving response speed of a liquid crystal element in caseof a liquid crystal display device, particular, improving response speedin case of rising.

[Means for Solving the Problem]

In the present invention, it is characterized that a liquid crystallayer is divided into plural regions (domains) substantially by mixing achemical compound including a liquid crystal skeleton in the liquidcrystal layer in which liquid crystal molecules exist as a technique toimprove response speed of a liquid crystal element in a liquid crystaldisplay device to solve the above problem. In addition, a liquid crystalskeleton is a structure portion of a liquid crystalline monomerincluding liquid crystal and a polymerizable group. The polymerizablegroup is not refered to as a liquid crystal skeleton by itself.

Specifically, a liquid crystal display device of the present inventionis characterized by including a pair of substrates each having anelectrode formed on one surface thereof, a liquid crystal layer, and apair of polarizing plates, in which the pair of substrates are arrangedso that the surfaces on which the electrodes are formed are on theinside and face each other; in which the liquid crystal layer issandwitched by the pair of substrates; in which the pair of substratesis sandwitched by the pair of polarizing plates; and in which the liquidcrystal layer includes a liquid crystal molecule and a compound havingliquid crystal skeleton.

Another structure of the liquid crystal display device of the presentinvention is characterized by including a pair of substrates each havingan electrode formed on one surface thereof, a liquid crystal layer, anda pair of polarizing plates, in which a projection is formed in one ofthe electrodes; in which the pair of substrates is arranged so as toface the electrodes each other; in which the liquid crystal layer issandwitched by the pair of substrates; in which the pair of substratesis sandwitched by the pair of polarizing plates; in which the liquidcrystal layer includes a liquid crystal molecule and a compound having aliquid crystal skeleton.

In addition, in each of the above structures, the structure in which anactive element which is connected electrically to the electrode isformed in either of the pair of substrates may be employed, and pluralelectrodes may be formed on the one of the substrates.

In each of the above structures, the chemical compound having the liquidcrystal skeleton, may have the rate of 5 wt % to 15 wt % as a weightratio with respect to the liquid crystal molecule.

In addition, the chemical compound having the liquid crystal skeletonincludes a liquid crystalline monomer or a liquid crystalline polymer,and the liquid crystalline monomer is obtained by combining an aclyloyloxy group with the liquid crystal skeleton while the liquid crystallinepolymer is obtained by polymerizing a liquid crystalline monomer byirradiation of ultraviolet rays (UV) or the like.

In addition, the liquid crystal skeleton is one of a biphenyls skeleton,a tolans skeleton, an esters skeleton, an alkenyls skeleton, acyclohexenes skeleton, azines skeleton, fluorine-containing condensedrings skeleton, and a naphthalenes skeleton.

EFFECT OF THE INVENTION

Since a force which affects an orientation of liquid crystal moleculesin a liquid crystal layer (frictional force or the like) can becontrolled, response time (in particular, falling response time when anelectric field is not applied) can be improved by performing the presentinvention.

Additionally, in the present invention, when a chemical compound havinga liquid crystal skeleton is mixed in a liquid crystal layer, pluraldomain regions can be formed in the liquid crystal layer withoutdisarraying an orientation of liquid crystal molecules included in theliquid crystal layer and an effect between liquid crystal molecules canbe suppressed.

Thus, in the structure of the present invention, since a response speedimproves, reduction of an after image can be improved and a displayquality can be improved. Note that, since a response speed improves, thepresent invention can be used for a display method which is expectedhigh speed operation such as a field sequential drive.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment Mode 1

This embodiment mode explains a case in which a liquid crystal layerincluding liquid crystal molecules are divided into plural regions as amethod for improving response speed of liquid crystal. FIG. 1 shows across section of a liquid crystal element in a liquid crystal displaydevice of the present invention and shows one of embodiment modes of thepresent invention. Reference numerals 101 and 102 are substrates, 103and 104 are electrodes, 105 and 106 are orientation films, 108 is aliquid crystal layer, 107 is a chemical compound having a liquid crystalskeleton, 109 is a spacer, and 110 is a sealing material.

The substrates 101 and 102 are materials which can transmit visiblelight and for example, glass, plastic, or quartz can be used. Whenoptical modulation of a liquid crystal material is controlled by anelectrical signal like the present invention, an electrode to beexplained hereinafter and a dielectric film to insulate an electrode arearranged over a surface of the substrate in an arbitrary form in somecases, however, a material which fulfills heat resistance and medicalsolution characteristics resistance is selected in order to manufactureand form at a desired specification. In addition, the substrate isrequired to have a thickness in which breakage does not occur byphysical shock to itself at the manufacturing process or further aftercompleating as a display element. For example, in the case of a glasssubstrate, a material with a thickness of 2 mm or less is preferablyused. At this point, a plastic plate can be formed thinner than glass.

Additionally, about light transmitting property of 101 and 102, when theliquid crystal display device is used as transmitting type, bothsubstrates need to have light transmitting property and when it is usedas reflecting type, at least one of them needs to have the property.

In addition, about the substrate it is desirable to use such a substratethat anisotropy of the refractive index is vanishingly small, besidesthe light transmitting property. This is for avoiding displayingunnecessary display property such that color tone is different dependingon a viewing angle or the like when optical anisotropy except a liquidcrystal material is included in the substrate.

A material having light transmitting property of visible light such asindium tin oxide is used for the electrodes 103 and 104. In particular,it is desirable to have transparency in a portion using opticalmodulation of a liquid crystal material. In addition, if one of theelectrodes has transparency of visible light, the other electrode needsconductivity, and light transparency is not a requirement.

Additionally, a portion which does not contribute to display or a wiringto supply an electrical signal does not have to be always a transparentelectrode.

In addition, an element having a structure in which only one pixelelectrode exsists in a region where liquid crystal is filled is shown inFIG. 1, however, it is not necessary to be always bounded by this, evenif plural pixels are formed on the substrate of the region in whichliquid crystal is filled, there is no problem.

An organic compound such as polyimide, DLC (diamondlike carbon), and aninorganic compound such as SiO₂ can be used as the orientation films 105and 106. Surfaces of the orientation films 105 and 106 are performedorientation treatment for orienting liquid crystal to a desireddirection according to need. Flatness of the surface of the orientationfilm is adjusted arbitrarily depending on liquid crystal which is used.Since nematic liquid crystal has a low viscosity, it may be flattened orconvexoconcave may be formed in an orientation film as shown in thisfigure because it follows a form of a surface of the orientation film ifthe orientation film has convexoconcave. Note that, a perpendicularorientation treatment that a major axis of a liquid crystal moleculebecomes perpendicular is performed as an orientation treatment of theorientation film in the present invention.

A nematic material can be used as liquid crystal of the liquid crystallayer 108. It is necessary that dielectric anisotropy of this liquidcrystal is negative.

The chemical compound having a liquid crystal skeleton 107 is includedin the liquid crystal layer 108. Note that, a liquid crystalline monomerand a liquid crystalline polymer are included in the chemical compoundhaving a liquid crystal skeleton 107.

Liquid crystalline monomer is a material which can orient by a normalliquid crystal orientation method like liquid crystal, in a monomericsubstance (monomer) state. Liquid crystalline monomer can be made apolymer by polymerization reaction as against a normal liquid crystalmaterial does not have reactivity in particular. Thus, when a liquidcrystalline monomer is performed polymerization reaction in theorientation state, a polymer that molecular sequence of the liquidcrystal skeleton is fixed while the orientation state is not changed,namely a liquid crystalline polymer can be formed.

Note that, a liquid crystalline monomer in the present invention isobtained by combining a liquid crystal skeleton with an acryloyl oxygroup, and a biphenyls skeleton, a tolans skeleton, an esters skeleton,an alkenyls skeleton, a cyclohexenes skeleton, an azines skeleton, afluorine-containing condensed rings skeleton, and a naphthalenesskeleton and the like are included in the liquid crystal skeleton here.

In the present invention, it is desirable that the chemical compoundhaving a liquid crystal skeleton 107 is mixed at the rate of 5 wt % to15 wt % in weight ratio as against a liquid crystal material forming theliquid crystal layer 108. Note that, it may be used as a liquidcrystalline monomer in this state, however, the liquid crystallinemonomer may be polymerized to form a liquid crystalline polymer byirradiating ultraviolet rays to or heating a liquid crystal materialwhich mixed the liquid crystalline monomer. In addition, a liquidcrystalline polymer exists with the state that arranged in the form ofinterspersion or network in the liquid crystal layer 108. The statewhich is arranged in the form of network means the state which forms aliquid crystalline polymer by polymerizing a polymerizable group of aliquid crystalline monomer dotted in the liquid crystal layer.

Note that, when the chemical compound having a liquid crystal skeletonexists in the liquid crystal layer 108, the liquid crystal layer 108 isdivided by the chemical compound having a liquid crystal skeleton 107which is arranged in the form of interspersion or network so that adomain is formed. In addition, a dimension of the domain is 100 μm orless. In other words, in the present invention, the state that liquidcrystal molecules separates and exists in the liquid crystal layer 108having plural domains is obtained. Accordingly, when an orientation ischanged, a dullness of response at orientating perpendicularly withoutapplying an electric field, in particular, can be improved since aneffect between liquid crystal molecules can be suppressed compared withthe case of existing liquid crystal molecules in the whole region of theliquid crystal layer 108.

The spacer 109 is a thing for keeping the substrate interval uniform,and a thing which can maintain a desired dimension of desired thesubstrate interval is used. A spacer is required to be a sphere andcolumn. Sectional composition of trapezoidal form may be used.

The sealing material 110 is formed so as to surround a liquid crystalmaterial for the purpose of bonding a substrate and preventing theliquid crystal material from flowing to the outside of the sealingmaterial. A sealing material is an adhesive, and, a thermo curing typematerial or a light curing type material can be used. In addition, anepoxy resin, an acrylic resin, and the like can be used.

A projection 111 may be formed on the electrode 104 of the liquidcrystal element. Note that, the projection 111 is a component that itsform further protrudes from the height of a surface of the pixelelectrode and it may be cylindrical form or wall form. Note that, a wordof “column form” of “wall form” to compare the form of a projection isused in this specification, and all of them are included in theprojection described in this specification. A wall form projection maybe formed to be plural wall forms which is straight line form judgingfrom a top view thereof and is parallel judging from a cross-sectionalview thereof in a display region, or may be formed in curb form tocompletely surround each of pixel electrodes. In addition, there may bea void between walls instead of wall form which is closed completely. Itmay be contact with respect to a counter substrate as shown in FIG. 2(A)and liquid crystal may exist between a counter substrate and aprojection like FIG. 2(B). A projection, a column, or a wall may be thesame cycle as a pixel. Additionally, a part of projection may beprotruded to a part of region of the pixel electrode in the range thatdoes not disturb display, however, it must not spread through the wholepixel electrode.

As a material for forming the projection 111, an inorganic compound andan organic compound can be used. As for the inorganic compound, SiO₂,SiN, SiON or the like is given and as for the organic compound, acrylicresin, epoxy resin, resist, divinylbenzene or the like is given. Notethat, adjacent pixel electrodes cannot display when they are notinsulated, therefore, it is required that the projection 111 is aninsulating substance.

In addition, the projection 111 may be formed by photolithography aftera constitution material of the projection is formed to be a film once byCVD method or sputtering method, or may be formed by using printing,ink-jet method, evaporation method or the like.

The liquid crystal layer 108 is arranged between the first substrate 101and the second substrate 102. The liquid crystal layer 108 is preferablyarranged under the vacuum. Alternatively, after being delivered a liquidcrystal layer by drops on the first substrate 101, the second substrate102 may be attached. Particularly, when it becomes a large-sizedsubstrate, it is preferable that a liquid crystal layer is fallen indrops than injected.

Embodiment Mode 2

Emobodiment mode 2 explained is a case in which a continuous pulse isapplied to a liquid crystal display device as a method to improveresponse speed of liquid crystal. Note that, about constitution and amanufacturing method of a liquid crystal display device, FIG. 1explained with Embodiment Mode 1 may be referred except that a liquidcrystal layer is formed by only a liquid crystal material (a chemicalcompound having a liquid crystal skeleton is not included).

In other words, when electric field is applied or electric field is notapplied, response speed of liquid crystal molecules can be improvedsince a constant oscillation is given to the liquid crystal moleculesexisiting in the liquid crystal layer by applying a pulse to the liquidcrystal display device repeatedly at regular time intervals. Note that,a pulse here is the voltage which is necessary that liquid crystalresponds and it is necessary that a duty ratio of the pulse (a ratio ofpulse application time to a cycle of applying the pulse) is 10% or less.

Embodiment 1

In this embodiment, a liquid crystal element including a chemicalcompound having a liquid crystal skeleton in a liquid crystal layer isformed as described in Embodiment Mode 1 and a result of evaluating anoptical property thereof is described.

Manufacturing of a liquid crystal element in this embodiment, a glasssubstrate that thickness was 0.7 mm and outline is 2 cm×2 cm is used. Onthe upper side of this glass substrate, an indium tin oxide film wasformed as a transparent electrode. The indium tin oxide film was used inan electrode part formed of 7 mm×7 mm form for driving liquid crystaland in an extraction electrode part for applying electric field toliquid crystal from outside. An orientation film for perpendicularorientation (SE1211 produced by Nissan Chemical Industries) was used asan orientation film to orientate a liquid crystal material. A thin filmof the perpendicular orientation film was formed on the upper side ofthe substrate and the film thickness thereof is 60 nm.

Next, the pair of substrates was attached with facing respective theelectrode parts on the upper sides of the substrates. The intervalbetween the pair of substrates is set to be 5 μm. A sealing materialcomposed of an epoxy resin was used as method to adhere and fixsubstrates together. The sealing material used here was obtained bymixing fiber of cylindrical form which contains SiO₂ as a maincomponent. A diameter of the fiber is 5 μm. After being attached acounter substrate, the extra portion which does not directly contributeto display of a substrate was cut-offed using a glass scriber and abreaker to form an element.

Commercial MLC2038 (produced by Merck) was used as nematic liquidcrystal. Liquid crystalline monomer UCL003 (produced by Dainippon Inkand Chemicals) was added in this liquid crystal. The mixing ratio ratewas adjusted so as to be 10 wt % in weight ratio with respect to theliquid crystal. This material was injected between the substrates whichhave been attached. The injection was performed by vacuum injectionmethod which is generally performed in manufacturing of a liquid crystalelement. After the injection, ultraviolet rays were irradiated.Ultraviolet rays had center wavelength of 365 nm and irradiatingintensity of 1.2 mW/cm². Accordingly, a liquid crystal element includinga liquid crystalline polymer in a liquid crystal layer was formed.

The response speed was evaluated by using the liquid crystal element.Note that, in this embodiment, the response speed of the liquid crystalelement was evaluated by applying a driving voltage to the liquidcrystal element between polarizing plates and measuring dimension ofchange of transmitting light intensity from a light source, afterarranging the liquid crystal element between the pair of polarizingplates which is arranged in a cross nicol manner and arranging lightsource downward the polarizing plate on the lower side and arranging aphotoelectron multiplier upward of the polarizing plate on the upperside.

Measurement result is shown in FIG. 4. In FIG. 4, time (response time)is plotted in a horizontal axis, transmitting light intensity is plottedin a vertical axis (right side), and an applied voltage is plotted invertical side (left side). Note that, transmitting light intensity (V)shown here shows a value obtained by measuring change of transmittinglight intensity (change of light intensity) from the light source whichis obtained by birefringence property of liquid crystal moleculesincluded in the liquid crystal element, as electric potential fromphotoelectric change and amplification of the photoelectron multiplier.

In this embodiment, when the liquid crystal element was driven with apulse of 4 ms and at applied voltage of 6 V, response time of liquidcrystal (rising response time) by pulse application was 2 ms andresponse time of liquid crystal (falling response time) by pulseelectric potential removal was 2 ms.

COMPARATIVE EXAMPLE 1

In this comparative example, measurement was performed in the samemethod as Embodiment 1 by using an element which was manufactured by themethod described in Embodiment 1 without adding a chemical compoundhaving a liquid crystal skeleton (liquid crystalline polymer) in theliquid crystal layer. The result is shown in FIG. 5. Therefore, such adimension that response speed becomes slow with time course incomparison with Embodiment 1 could be confirmed.

Embodiment 2

In this embodiment, described is the result of evaluating an opticalproperty in the case where a liquid crystal element is manufactured asdescribed in Embodiment Mode 2 and a continuous pulse is applied.

Note that, commercial MLC2038 (produced by Merck) which is nematicliquid crystal was used for a liquid crystal layer of the liquid crystalelement.

Applied voltage was fixed at 6 V to this liquid crystal element and itwas driven with a pulse of pulse width of 4 ms. A pulse was appliedrepeatedly, and when interval of the pulse was controlled and responsetime was measured, orientation of liquid crystal was divided intomini-region at duty ratio (the ratio of pulse application time and timeof one period of pulse driving waveform) in one period of pulse drivingwaveform becomes relational of less than or equal to 10%. Orientationstate of liquid crystal in this time is shown in FIG. 6(A).

When duty ratio was 8%, response time of liquid crystal (rising responsetime) by pulse application in this time was 2 ms as shown in FIG. 6(B)and response time of liquid crystal (falling response time) by pulseelectric potential removal was 2 ms.

COMPARATIVE EXAMPLE 2

On the other hand, when the duty ratio in Embodiment 2 is larger than10%, the falling response time of the response time of liquid crystalbecame 20 ms or more in some cases. The result in the case where theduty ratio is 18% is shown in FIG. 7. In addition, the orientation stateof liquid crystal in this time showed orientation which is generallyreferred to as schlieren texture as shown in FIG. 8. Note that, anenlarged image of liquid crystal molecules 800 in a schlieren texturephotography of FIG. 8(A) is shown in FIG. 8(B).

Embodiment 3

In this embodiment, described is an example when the present inventionis applied to a liquid crystal display device of active matrix type. InFIG. 3(A), a liquid crystal display device in which a signal line drivercircuit 230, a scanning line driver circuit 238, and a pixel portion 231are formed over a first substrate 200 is shown.

FIG. 3 (B) shows a cross-sectional view of A-A′ of the liquid crystaldisplay device and the signal line driver circuit 230 providing a CMOScircuit having an n-channel type TFT 221 and a p-channel type TFT 222over the first layer 200 is shown. The n-channel type TFT 221 and thep-channel type TFT 222 is preferably formed so that they have acrystalline semiconductor film. A TFT which forms the signal line drivercircuit 230 or the scanning driver circuit 238 may be formed by a CMOScircuit, a PMOS circuit, or an NMOS circuit.

The pixel portion 231 has a switching TFT 223 and a capacitor element258. The switching TFT 223 is preferably formed to have a crystallinesemiconductor film. The capacitor element 258 is constituted by a gateinsulating film sandwiched between a semiconductor film added withimpurities and a gate electrode.

Note that, a TFT of the pixel portion 231 does not have to have highcrystallinity as compared to the signal line driver circuit 230 and thescanning line driver circuit 238.

In addition, the pixel portion 231 has a pixel electrode 211 which isconnected to one of electrodes of the switching TFT 223. In addition, athird insulating film 209 is provided so as to cover the n-channel typeTFT 221, the p-channel type TFT 222, the pixel electrode 211, the TFTfor switching 223 and the like.

Additionally, a second substrate 245 corresponding to a countersubstrate is prepared. A black matrix 251 is formed in a positioncorresponding to the signal line driver circuit 230 at least, and acolor filter 252 is formed in a position corresponding to at least apixel portion, and further, a counter electrode 253 is formed over thesecond substrate 245. The present invention does not have to alwaysprovide a black matrix, a color filter, or a counter electrode over thesecond substrate 245, and it may be provided on the first substrate 200side. After this, a spacer 256 for keeping substrate interval may alsobe formed. In addition, a projection 250 for preventing convection of aliquid crystal material may be formed at the same time for the purposeof preventing that bias of distribution of a chemical compound having aliquid crystal skeleton (liquid crystalline monomer, liquid crystallinepolymer) included in a liquid crystal layer 254 from arising.

The spacer 256 may also use a spherical thing, or can use so-called acolumn spacer which is formed by etching an insulating film. Further,height of the projection 250 is made same as a thickness of the liquidcrystal layer 254 and may be provided the same function as the spacer256, and it can be selected suitably whether the spacer 256 and theprojection 250 is separated or conformed. Next, the second substrate 245is performed orientation treatment and attached using a sealing material243 to the first substrate 200. It is preferable for the sealingmaterial 243 to use an epoxy system resin. In addition, a part of thethird insulating film 209 may be left in a position for forming thesealing material 243. Accordingly, adhesion dimension is large andadhesion intensity can be improved. Note that, the spacer 256 forkeeping substrate interval may be formed after orientation treatment isperformed to an orientation film.

The liquid crystal layer 254 is injected between the first substrate 200and the second substrate 245. When the liquid crystal layer 254 isinjected, it may be performed under the vacuum. In addition, the secondsubstrate 245 may be attached after a liquid crystal layer is deliveredon the first substrate 200. Particularly, when in the case of alarge-sized substrate, it is preferable that a liquid crystal layer isfallen in drops than injected. Note that, a chemical compound having aliquid crystal skeleton 255 is included in the liquid crystal layer inthe present invention, however, a liquid crystalline polymer which isobtained by polymerizing a liquid crystalline monomer can be used aswell as a liquid crystalline monomer as the chemical compound 255 havinga liquid crystal skeleton. In this embodiment, it is decided to use aliquid crystalline monomer.

A polarizing plate or a circularly polarizing plate may be providedarbitrarily to the first substrate 200 and the second substrate 245 toimprove a contrast.

In addition, a flexible print circuit (FPC) 246 is connected to aconductive film 208 provided in a first connection region 232 by ananisotropic conductive resin (ACF). A video signal and a clock signalwhich correspond to an external input signal through the FPC 246 arereceived. Only the FPC is shown here, however, a printed wiring board(PWB) is provided through this FPC. And an external signal generationcircuit is mounted to a printed wiring basis.

In addition, when ACF is adhered by pressurization or heating, it isnecessary to careful not to arise a crack by flexible characteristic ofa substrate or softening by heating. For example, a high rigiditysubstrate may be arranged as support at least at a lower position of thefirst connection region 232.

In this embodiment, a driver built-in type liquid crystal display devicein which the signal line driver circuit 230 and the scanning line drivercircuit 238 are provided over the first substrate 200 is described,however, the signal line driver circuit and the scanning line drivercircuit may be formed by IC, and may be connected to a signal line, ascanning line or the like by SOG method or TAB method.

As the above, a liquid crystal display device having an active matrixsubstrate can be manufactured.

Embodiment 4

Electronic apparatuses providing the liquid crystal display device ofthe present invention include such as a television set (just referred toas television or television receiver), cameras such as a digital cameraand a digital video camera, a mobile phone set (just referred to as amobile phone or a cell-phone), a portable information terminal such as aPDA, a portable game machine, a monitor for a computer, a computer, anaudio reproducing device such as a car audio system, and an imagereproducing device provided with a recording medium such as a home gamemachine. Its specific examples are described with reference to FIG. 9.

A portable information terminal apparatuse shown in FIG. 9(A) includes amain body 9201, a display portion 9202 and the like. The liquid crystaldisplay device of the present invention can be applied to the displayportion 9202. Accordingly, high speed response is enabled and a portableinformation terminal apparatuse in which a moving-image displaycapability is improved can be supplied.

A digital video camera shown in FIG. 9(B) includes a display portion9701 and a display portion 9702 and the like. High speed response isenabled by using the liquid crystal display device of the presentinvention to the display portion 9701 and a digital video camera inwhich a moving-image display capability is improved can be supplied.

A mobile phone shown in FIG. 9(C) includes a main body 9101, a displayportion 9102 and the like. High speed response is enabled by using theliquid crystal display device of the present invention to the displayportion 9102 and a mobile phone in which a moving-image displaycapability is improved can be supplied.

A portable television device shown in FIG. 9(D) includes a main body9301, a display portion 9302 and the like. High speed response isenabled by using the liquid crystal display device of the presentinvention to the display portion 9302 and a portable television devicein which a moving-image display capability is improved can be supplied.In addition, the liquid crystal display device of the present inventioncan be applied to a broad range of television devices from a small-sizeone mounted onto a portable terminal such as a mobile phone to amedium-size one which can be taken along, in addition, a big-size one(for example, more than 40 inches).

A portable computer shown in FIG. 9(E) includes a main body 9401, adisplay portion 9402 and the like. High speed response is enabled byusing the liquid crystal display device of the present invention to thedisplay portion 9402 and a portable computer in which a moving-imagedisplay capability is improved can be supplied.

A television device shown in FIG. 9(F) includes a main body 9501, adisplay portion 9502 and the like. High speed response is enabled byusing the liquid crystal display device of the present invention to thedisplay portion 9402 and a portable computer in which a moving-imagedisplay capability is improved can be supplied.

In this manner, high speed response is enabled by using the liquidcrystal display device of the present invention and an electronicappratuse in which a moving-image display capability is improved can besupplied.

INDUSTRIAL APPLICABILITY

It can be used to a display device requiring high speed response such asa display which performs moving-image display mainly.

This invention is based on Japanese Patent Application serial no.2004-352264 filed in Japan Patent Office on 6th, Dec., 2004, the entirecontents of which are hereby incorporated by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram explaining a cross section of a liquid crystalelement;

FIGS. 2A and 2B are diagrams each explaining a cross section of a liquidcrystal element;

FIGS. 3A and 3B are diagrams explaining a cross section of a liquidcrystal display device;

FIG. 4 is a diagram which shows a result measured for electricalcharacteristic of a liquid crystal element;

FIG. 5 is a diagram which shows a result measured for electricalcharacteristic of a liquid crystal element;

FIGS. 6A and 6B diagrams which show state of a liquid crystal layer anda measurement result for electrical characteristic of a liquid crystalelement respectively;

FIG. 7 is a diagram which shows a measurement result for electricalcharacteristic of a liquid crystal element;

FIGS. 8A and 8B are diagrams which show state of a liquid crystal layerof a liquid crystal element, and

FIGS. 9A to 9F are diagrams which show electronic apparatuses usingliquid crystal display devices.

1. A liquid crystal display device comprising: first and secondsubstrates opposed to each other; a first electrode formed over thefirst substrate; a second electrode formed over the second substrate; aprojection formed over the first electrode; a first orientation filmformed over the first electrode; a second orientation film formed overthe second electrode; a liquid crystal layer located between the firstand second orientation film; and a pair of polarizing plates with thefirst and second substrates interposed therebetween, wherein the liquidcrystal layer includes a liquid crystal molecule and a compound having aliquid crystal skeleton, wherein the liquid crystal layer includes aplurality of domain regions, and wherein the first orientation filmcontacts the second orientation film between the projection and thesecond substrate.
 2. A liquid crystal display device comprising: firstand second substrates opposed to each other; a first electrode formedover the first substrate; a second electrode formed over the secondsubstrate; a projection which is a straight line formed over the firstelectrode; a first orientation film formed over the first electrode; asecond orientation film formed over the second electrode; a liquidcrystal layer located between the first and second orientation film; anda pair of polarizing plates with the first and second substratesinterposed therebetween, wherein the liquid crystal layer includes aliquid crystal molecule and a compound having a liquid crystal skeleton,wherein the liquid crystal layer includes a plurality of domain regions,and wherein the first orientation film contacts the second orientationfilm between the projection and the second substrate.
 3. A liquidcrystal display device comprising: first and second substrates opposedto each other; a first electrode formed over the first substrate; asecond electrode formed over the second substrate; a projection which isa straight line formed over the first electrode; a first orientationfilm formed over the first electrode; a second orientation film formedover the second electrode; a liquid crystal layer located between thefirst and second orientation film; a pair of polarizing plates with thefirst and second substrates interposed therebetween; and an activeelement electrically connected to the first electrode, wherein theliquid crystal layer includes a liquid crystal molecule and a compoundhaving a liquid crystal skeleton, and wherein the liquid crystal layerincludes a plurality of domain regions, and wherein the firstorientation film contacts the second orientation film between theprojection and the second substrate.
 4. A liquid crystal display devicecomprising: first and second substrates opposed to each other; aplurality of first electrodes formed over the first substrate; a secondelectrode formed over the second substrate; a projection which is astraight line provided between the plurality of first electrodes; afirst orientation film formed over the plurality of a first electrodes;a second orientation film formed over the second electrode; a liquidcrystal layer located between the first and second orientation film; apair of polarizing plates with the first and second substratesinterposed therebetween; and a plurality of active elements electricallyconnected to the plurality of first electrodes, respectively; whereinthe liquid crystal layer includes a liquid crystal molecule and acompound having a liquid crystal skeleton, and wherein the liquidcrystal layer includes a plurality of domain regions, and wherein thefirst orientation film contacts the second orientation film between theprojection and the second substrate.
 5. A liquid crystal display deviceaccording to claim 1 wherein the compound having the liquid crystalskeleton has a weight ratio at 5 wt% to 15 wt% with respect to theliquid crystal molecule.
 6. A liquid crystal display device according toclaim 2 wherein the compound having the liquid crystal skeleton has aweight ratio at 5 wt% to 15 wt% with respect to the liquid crystalmolecule.
 7. A liquid crystal display device according to claim 3wherein the compound having the liquid crystal skeleton has a weightratio at 5 wt% to 15 wt% with respect to the liquid crystal molecule. 8.A liquid crystal display device according to claim 4 wherein thecompound having the liquid crystal skeleton has a weight ratio at 5 wt%to 15 wt% with respect to the liquid crystal molecule.
 9. A liquidcrystal display device according to claim 1 wherein the liquid crystalmolecule shows a perpendicular orientation.
 10. A liquid crystal displaydevice according to claim 2 wherein the liquid crystal molecule shows aperpendicular orientation.
 11. A liquid crystal display device accordingto claim 3 wherein the liquid crystal molecule shows a perpendicularorientation.
 12. A liquid crystal display device according to claim 4wherein the liquid crystal molecule shows a perpendicular orientation.13. A liquid crystal display device according to claim 1 wherein thecompound having the liquid crystal skeleton is a liquid crystal monomeror a liquid crystal polymer.
 14. A liquid crystal display deviceaccording to claim 2 wherein the compound having the liquid crystalskeleton is a liquid crystal monomer or a liquid crystal polymer.
 15. Aliquid crystal display device according to claim 3 wherein the compoundhaving the liquid crystal skeleton is a liquid crystal monomer or aliquid crystal polymer.
 16. A liquid crystal display device according toclaim 4 wherein the compound having the liquid crystal skeleton is aliquid crystal monomer or a liquid crystal polymer.
 17. A liquid crystaldisplay device according to claim 13 wherein the liquid crystal monomeris obtained by bonding a liquid crystal skeleton to an acrlyloyl oxygroup.
 18. A liquid crystal display device according to claim 14 whereinthe liquid crystal monomer is obtained by bonding a liquid crystalskeleton to an acrlyloyl oxy group.
 19. A liquid crystal display deviceaccording to claim 15 wherein the liquid crystal monomer is obtained bybonding a liquid crystal skeleton to an acrlyloyl oxy group.
 20. Aliquid crystal display device according to claim 16 wherein the liquidcrystal monomer is obtained by bonding a liquid crystal skeleton to anacrlyloyl oxy group.
 21. A liquid crystal display device according toclaim 13 wherein the liquid crystal polymer is obtained by polymerizingthe liquid crystalline monomer.
 22. A liquid crystal display deviceaccording to claim 14 wherein the liquid crystal polymer is obtained bypolymerizing the liquid crystalline monomer.
 23. A liquid crystaldisplay device according to claim 15 wherein the liquid crystal polymeris obtained by polymerizing the liquid crystalline monomer.
 24. A liquidcrystal display device according to claim 16 wherein the liquid crystalpolymer is obtained by polymerizing the liquid crystalline monomer. 25.A liquid crystal display device according to claim 1 wherein the liquidcrystal skeleton is one of a biphenyls skeleton, a tolans skeleton, anesters skeleton, an alkenyls skeleton, a cyclohexenes skeleton, azinesskeleton, fluorine-containing condensed rings skeleton, and anaphthalenes skeleton.
 26. A liquid crystal display device according toclaim 2 wherein the liquid crystal skeleton is one of a biphenylsskeleton, a tolans skeleton, an esters skeleton, an alkenyls skeleton, acyclohexenes skeleton, azines skeleton, fluorine-containing condensedrings skeleton, and a naphthalenes skeleton.
 27. A liquid crystaldisplay device according to claim 3 wherein the liquid crystal skeletonis one of a biphenyls skeleton, a tolans skeleton, an esters skeleton,an alkenyls skeleton, a cyclohexenes skeleton, azines skeleton,fluorine-containing condensed rings skeleton, and a naphthalenesskeleton.
 28. A liquid crystal display device according to claim 4wherein the liquid crystal skeleton is one of a biphenyls skeleton, atolans skeleton, an esters skeleton, an alkenyls skeleton, acyclohexenes skeleton, azines skeleton, fluorine-containing condensedrings skeleton, and a naphthalenes skeleton.